Photometric calculator



J. M. BI'NG j l PHOTOIETRIC CALCULATOR Filed Aug.

June 21, 193:1.

2 .sheets-sheet 1` Isa, 1929 lua l xxxxxx FILTER tml ACTORS xxxxxx MUD FILTER FAcToRs INVENTOR ATTQRNEYS J. M. BING PHOTOMETRIC CALCULATOR Filed Aug. 9. 1929 I l M Is-I I g I l .r

ig I I l -IIIIi M L l :l IEI.

Jun 21, 1932.

Patented June 21, 14932v JOSEPH MrBING, OF NEW YORK, N. Y.

PHOTOMETRIC CALCULATOR Application illed August 9, 1929. Serial No. 384,599.

My invention relates to a new and useful im rovement in a photometric calculator.

(Ilne of the objects of my invention is to provide a scale system which can be used with photometers of the type shown in Reissue U. S. Patent No. 16,879, dated February 14th, 1928, and application Ser. No. 204,180 filed July 8th, 1927', on which U. S. Patent No.

1,738,354has been issued, although it is to.,` 10 be understood that my scale system may be utilized in connection with any kind of photometer, and that it can also be utilized independently of a photometer. u

Another object'of my invention is to pro- 1 vide a scale system in connection with a pho-A` tometer, or independently thereof, whereby' a reading will be automatically secured to make the proper adjustment of the camera so as -to compensate for the use of different corrective filters yor screens, the use of recording plates or films having` different emulsion speeds, and other variable factors which may enterV into phot-ography.

Another object of my invention is to provide a scale system whereby direct reading can be securedof the correct lens aperture of the camera, expressed by the customary relative stop value number or f number.

" Anotherobject of my invention is to provide a scale system which can be-used in con- 30 nection with still photography or kinematic photography. 4

Another object of my invention is to provide a scale system in which therespective elements may be' arranged in any suitable r relative position. For example, the specificl embodiment later disclosed, shows the elements as arranged in concentric circles, but said elements may be arranged in the form' of planar, parallel strips.

vention is intended merely to generally explain the same.

Fig. 1 is an elevation showing my inven,

l' tion applied to a photometer of the type shown in Reissue U. S. Patent No. 16,87 9 and application Ser. No. 204,180.

Other objects of my'invention will be setv general statement of the objects of my in- Fig. 2 is a diagrammatic view showing the scale system as utilized in still photography, and applied to a photometer o the extinction'type as shown in said Reissue U. S. Patent N o. 16,879 and application Ser. No. 204,180. In this embodiment the'correct expcsure condition is indicated by the position of an index ontlie iris collar of the photometer. The system may apply to photography without the use ofv filters, and with the use ofa photographic film of par speed, or extra rapid film of the usual kind.

Fig. 3y shows the same system applied to stlill photography, and showing the use of a ter. 1

Fig. 4 shows the same system applied to still photography, and showing theuse of a hofographic plate or film which is much aster than the par type previously mentioned.

Figs. 5 and 6 diagrammatically illustrate certain mechanical details.

Fig. 7 shows the system as utilized in connection with still photography in which allowance is made for the combined Iuse of a filter, and a change in the speed of the film or plate used in the camera.

Figs. 8, 9 and 10 show the use of the sysvtem previously mentioned, as applied to kinematic or motion vpicture photography.

As shown in Fig. 1, the photometer 1 may t be of any suitable type, as for example, the

.type shown in Reissue U. S. Patent No. 16,879

and application Ser. No. 204,180. This type of instrument is provided with an iris diaphragm and with a field or fields of varying permeability, through which the light is allowed to shine. The iris diaphra of the instrument is manipulated until t e proper field is no longer visible, andthe setting of the iris diaphragm of the instrument then indicates the setting of the iris diaphragm of the camera, in accordance with the light conditions present.

According to this'invention the photometer is provided withl scales v2, 3 and 4 which consist of concentric collars.` The use. of these three scales makes it possible to secure direct reading for the various comhina-tions of filter factors, emulsion speed,

andlens aperture. The variation in filter y factors is due to the various corrective lters -or screens used in front of the camera lens, to

Y metallic silver or the like, when the plate or film: is developed. The lens aperture or f number limits the amountof light admitted y into the camera and this is usually regulated by an iris diaphragm, which is one type of variable masking contrivance. -1

These three principal factors which enter into the photographic conditions can be separately or jointly considered, to provide a direct reading by a single movement of one Vofthe scale elements, namely, the serale' ele- -ment which brings the f number into such alignment a-nd` position that an indicatori` shows the correct f number .for the iris da phra of the camera lens, which preferabl as a similar scale. y

' o r example, in Fig. 2, the three rings 2, 3 and 4 are shown as beingvdeveloped into planar form. Auming that the plate emloyed hasfpar speed, which is sometimes eslgnated as extra rapid, the second or intermediate ring3 is manipulated until thex designation par is Vin alignment with the `arrow index .6 on-the rst ring 2. The index' 5 which showed the setting of the iris dia- 4indicated as Filter factors, indicate filters .tive relation aa that between successive phragm of the V hotome'ter then points to the stopnumber fgS This corresponds to normal exposure for.

photometers of the type above mentioned, be-

cause their-.normal reading c 'rresponds to the use of par speed film uti ized without a filter. The aperture control of this type of instrument is by means of an' iris diaphragm or a s iral split. If controlled by an iris, then t e reading of the scale indicates the relative stop values, in the customary f 'svstem which isa geometric progres- Y sionin which adjacent stop numbers 4indicate one half-or double time.- Hence, thedistances between. thevarious stop vvnumbers would not be equal, but these unequally spaced numbers of the'index are converted into a scale of equal parts by the guide lines 7. A scale indicating-the various filter factors is also located upon the fixed first ring 2, which carries the guide lines 7. Th'e spaces between the indications of the various filter' factors are thesame and have the same rela- 'de lines 7. The large numbers on the scale of greater density and of smaller light rmeability. -Hence, the aperture ofgthe' ens must increase in proportion to the density of the filter so that the stop number must decrease, as the desnity of the filter is increased, because a smaller stop Vnumber indicates a greater lens aperture.

The adjustment of the scale system is effected by shifting the second or intermedi-4 ate ring?, in the clockwise direction.

For example, if a 4-time filter is to be utilized, the intermediate ring 3 is shifted, as shown in Fig. 3, until the designation par is inalignment with the desi ation 4m on the scale of filter factors. his causes the scale of stop numbers to be shifted by two numbers so that the guide line '7l which now registers with the index 5, points to the number 4 on the scale of stop numbers, instead of pointing to the number 8 which is the condition indicated in Fig. 2. Hence, if the diaphragm or other means for regulatn the aperture of the camera lens is correspon ingly adjusted, four times as much ligh'this caused to apt upon the sensitized plate or film, so as to compensate for the employment of the 42:

filter. As shown in Fig. 4, the scale system may be adjusted to show the compensation r ulred for dphotographic emulsions of di erent spee s. For example, in Fig. 4, the intermediate ring 3 has been adjusted so that the index 6 points to the designation Extr which correspondstoanemulsionofextreme speed, which is four times faster than par speed. Asshown in Fig, 4, since the designation Ext-r is now in alignment with index 6, the scale of stop numbers is also automatically shifted to the right, or in the clockwise direction, so that the index 5 now points t0 the stop number 16. This corresponds to a smaller lens aperture so as to compensate for the use of the faster emulsion. The stop f :16 corres nds to one-fourth' of the light admitted by t e former stop f :8 used wlth a isst speed emulsion. I

shown in Fi a 7, a combination of vvariations in the use o filter and emulsion can be taken care of by the system. For example, Fig. 7 illustrates the use of a slow emulsion which requires four times the exposure of par emulsion. "Likewise, a 2-time filter is to be utilized. The intermediate ring 3 is therefore shifted until the designation Slow registerswith the designation 2z on the ring 2. This causes the original or normal stop number 8 to be shifted for a distancecorres nding to three whole stops so that theinfiii; 5 now points to the stop number 2.8jwhich causes eight times as much light to be admitted to the lens, so as to compensate for a plate or -film which is four vuse of the filter. v

The third or time ri 4 can be manipulated so as to allow for variation of the exposure time or shutter speed. For example, the Anor- -times slower, and to also compensate for the mal conditions shown in Fig. 2 .may correspond for example, to 1/25 of a second exposure time.

As shown in Fig. 2, this designation on the time ring 4 is provided with an index 9 a second is selected, then the proper stop value would be 2.8 instead of the stop value 4 indicated by the index 5 and the corresponding guide line 7. The adjustment of the diaphragm associated with the camera lens, corresponding tothe stop value 2.8 would increase the amount of light available for the exposure, so as to make proper allowance for the decrease in exposurek time. lllt is to be understood that the scale system previously discussed, is for use in still photography, and that the embodiment shown in Figs. 8-10 is to be used for kinematic photography. In kinematic photography the scale 2 is the same as before, butthe ring 3 is replaced by a ring 3a having a scale which indicates the exposures per second. The ring 4 is replaced by a ring 4a having a different scale.

In most motion picture cameras, filters are employed which act like the filters previously mentioned. This scale is indicated upon the first or fixed ring 2, which remains fixed as 1 in the system utilized in connection with still photography- The scale illustrated is that used in connection with the photometer shown in said Reissue U. S. Patent No. 16,879 and application Ser. No. 204,180, but the scale could be varied in accordance with the type of photometer or exposure meter utilized.

1* Likewise, the tables and charts now used independently of photometers or exposure meters, or actinometers lcould also have this automatic scale system incorporated therein.

In order to allow for the use of filters, the lmovable stop numbers shown on the ring 3a must be shifted to the left ,so as to causel smaller stop numbers to be used in accordltu" ance with 't employed.

Motion pictures are ordinarily taken at a so-calle'd normal frequency of sixteen per second, and the are normally projected at the same rate. owever, other speeds may be utilized. For example, the speed may be as low as eight frames per second, so as to produce accelerated motion when the pictures are projected at a normal frequency of sixteen per second. Likewise, the pictures may be taken at a rate which is a multiple of the normal frequency (such as 32, 48, 64 frames per increasingdensity of the filter second), so as to produce a slow-motion efect when the film is projected at the normal fre quency of sixteen per second. If the number of exposures per second is decreased, the frame is subjected to the action of light for a longer period,a so that a smaller lens aperture should be utilized. On the contrary, if the number of exposures per second is increased, then each frame or picture will have a shorter exposure time, and more light must be ladmitted which corresponds to a smaller stop number. Hence, the second or intermediate ring is moved to the right to allow for the decrease'in the number of frames taken per second, so as to bring a larger stop number in registration with the index 5 through the corresponding guide line 7. If the number of frames taken per secon-d is increased, the intermediate ring 3a is moved to the left,

or in the counterclockwise direction, thus,

causing a smaller stop number, which corresponds to a larger lens aperture, to register with the index 5 through the corresponding guide line 7. It is to be understood that the index 5 is connected to the ring 5a which controls the adjustment of the iris diaphragm of the Photometer, in the particular embodiment described.

For example, Fig. 8 corresponds to a normal taking speed of sixteen exposures per' second. and without the use of a filter. Hence, the designation 16 on the scale of the ring 3a is caused to register with the index arrow 6, and the guide line 7 which registers with the in'dex'mark 5, therefore points to the stop number 4.

Fig. 9 shows the change in conditions if a 2-t'ime filter is'employed. The intermediate ring 3a is shifted until the said designation 16 isin alignment with the designation 2m on the first or fixed ring 2. The guide line 7 which is now in alignment with the index mark 5, points to the stop number 2.8, so that double the amount of light is admitted into the camera, to compensate for the loss of light resulting from the employment of the filter. i

If the pictures are being taken at the rate of 32 frames per second, instead of the normal frequency of 16 framesfper second, then each individual frame or picture only has one-half the exposure time. Under such conv ditions, the designation 32 on the intermediate ring 3a can be shifted tobe in alignment withthe index arrow 6 on the fixed ring 2, which will cause the guide line 7 which is in alignment with the index mark 5, to again point to the stop number 2.8.

Fig. 10 shows the use of the system if the index 5 would point to -a sto number of apr' the designation 2m on the fixed ring'2, so

that the guide line 7 which is in ali ment with the' index 5 thereupon points to t e stop number 2, which .corresponds to the admission of four times as much light as the original stop number 8.

The system is also designed so as to make special allowance for the Kodacolor system of pictures which employs a color filter, which is approximately 30w This requires a lens aperture correspondin to f: 2 In view of the employment of a ter having the value above mentioned in the Kodacolor process, the amount of light which ultimately reaches the film has the effective value of the stop number 11.3, because the exposure .time corresponding to the relative stop values varies according to the squares of the stop numbers.

Hence, Kodacolor pictures can be fsecured only .under such conditions that the exposure on regular black and white film would vrequire a stop value of approximately 11.3,

namely, if the illumination used would `re quire such a sto value.

As shown in igs. 8-10, the portion of the stop scale adjacent the designation 11.3 is distinctively marked, as for example, by coloring the same, this color being indicated by the designation Col. By thus designating this portion of the stop scale, byl causin it to contrast with the remainder thereo this portion of the stop scale can be immediately observed on determining normal exposure with the type of photometer or ex posure meter before mentioned, or with other types of exposure meters, or with tables or slide rules, or actinometers, of the wedge or extinction or re-appearargbe type.

For example, in Fi 8the index 5 points to the stop number 4 ,This is to the right of what may be designated as Kodacolor field, and Kodacolorphoto raphy would not be successful because the lm would be very much underexposed. If however, the guide line 7 which is in alignment with the proximately 11.3, then t e Kodacolor can be exposed.

If the light is articularly good so'that a stop as small as f: 16 would be utilized in ordinary motion picture photography, a solcalled neutral densit l filter isi introduced into the Kodacolor process, in order to prevent over-exposure. l

As shown in Figs. 8, 9 and 10, this would correspond to that portion of the scale on the intermediate ring 3a, which is to-the left of the Kodacolor section, this 'ortion of the scale being indicatedI by D guide line" 7 which is in alignment with the index 5 points to the portion of the scale-corl responding to the designation-DF, then the uphotographer is immediately warned to use the neutral density iilter.

If the- The above explanation' is based on' the assumption that the normal taking speed of .16 exposures per second is utilized. However the scale system will automatically supply the proper information for the use of the Kodacolor at any taking speed.

For example, vif the speed is reduced to 8 exposures per second, then the designation 8'on the ring 3a is shifted from the position indicated in Fig. 8 until it is in alignment with the index arrow 6 on the fixed ring 2. This would cause the scale of stop numbers to be shifted by a scale unit,

so that the Kodacolor field, to ether withthe designation 11.3 assumes t e position formerly occupied yby the designation 8. This will show that Kodacolor work is possible when the light is such that the guide 'IISv stantly shown by the improved scale system.

When 'the color indicator field is thusmoved, the corresponding designation for the neutral densit filter is also correspondingly shifted, so t at this indication is likewise direct and automatic. The third or time ring 4a is utilized like the time ring referred to in the first embodiment, in connection with still photography. The basic time corresponding to normal exposure is adapted as the basis for this system. For example, if the frames are being taken at normal frequency, and the shutter employed in the motion picture camera has the usual open sector an le .of 180, and the normal exposure time or each frame is 1/32 of a second, then the indication correspondin to this, as shown in Fig. 8, is caused to aign with the stop number 4 Y Referring tothe scale indicated on rin 3a, at the right hand side of Figs. 8, 9 an 10, the designation S S appears directly adjacentthe number 8, indicatin super speed emulsion. Likewise, the deslgnation R appears' adjacent the number designate regular speed film. By shifting i corresponding scale could be utilized aving figures representing the openings of the shutter sectorsin rotary shutters, because said openings ma be variable at the option of the operator, an said openings are thus variable in most cameras used for professional work.

Thus, the designation 1/32 could be reresponds to an-f-` exposure time of 1/32 of a second if the frames are taken at' normal frequency. l

Likewise, the smaller and larger angles of shutter openings could be transformed into resulting time, the smaller angles being indicated at the right and the larger angles being indicated at the left of the designation 180. Hence, the proper stop number could be selected for any angle which was being utilized,

while properly correlating the filter factors' and the taking speed.

In connection with the previous explanation, it has been assumed that the scale rings have been shifted before the exposure meter is utilized to take the necessary reading. However, the scale system will operate lin exactly-the same manner and just as ready to automatically determine the proper lens aperture, if normal exposure has been preliminarily determined. If Vit is then deter mined to use filters, or to make any changes in conditionsA present, the system canbe utilized to re-establish or change theproper lens aperture. provided by the scale system, remains permanent until it ischanged by the operator, so that itis not necessary to memorize the reading after setting the exposure meter and before setting the camera.

In order to mechanically align the scale markings, the second ring 3 may be provided with a pair of tongues or projections T, as shown in Fig. 5. Each of these tongues T are provided by suitably stamping the said ring 3 so as to render said tongues T resilient. The

tongues T t into recesses in the support S, and the tongues are so arranged that when one of them enters one of said recesses, so that one of the guide lines 7 registers with the index 5, the other of said tongues T is intermediate two of said recesses. As shown in Fig. 5, said tongues T can slide in a groove i provided in a carrier S, said grooves being provided with spaced openings so that said tongues T serve to retain the ring 3 upon the carrier, while permitting a proper turning movement thereof. Hence, when the ring 3 lis turned for a distance corresponding to half the distance between the ends of adjacent lines 7, a slight but definite resistance is of fered to thefurther turning of the rin 3. Due to the resilience of the tongues T, t ey snap into and out of the openings in the carrier S, as the ring 3 is turned. Likewise, when the ring 3 is moved to the designated posltion, the tongues T hold it in said position because the tip of one of said tongues has then entered the corresponding opening O.

As shown in Fig. 6, the ring 3 may be provided with a projection P. in order to more readily manipulate the same.

If desired, the rings 4 and 4a could lbewoor- Likewise, the information structed likethe rings 3 and 3a, in order to enable the same to be shifted.

ItD will be no'tedthat the outerends of the Cguide lines 7, that is, those ends which irectly adjacent the scale of stop values, are equally spaced. On the contrary, the inner ends are. unequally spaced, so that the collar 5a; which controls the adjustment of the iris diaphragm. or similar control device -of the photometershown in Fig. 1, can be moved in the ordinary manner for normal reading.

While I havel` described the ring or scale member 2 as being fixed, the ring or scale members 3 and 3a being movable, the important factor is the relative movement between the various scale members illustrated, and my invention covers all devices having the necessary relative movement or movements.

The various scales other than the scale of stop numbers, may for convenience be described as scales of photographic conditions?, since each of them indicates one of the conditions which affects the proper stop value to be utilized for taking the exposure.

While I have referred to certain definite scales in the claims, it is to be understood that the invention is not to be limited to the specific scales illustrated herein, as such scales merely serve to illustrate vthe various uses o the improved device.

I have shown a complete combination or system describing the best embodiments of =my invention, but it is obvious that certain .sub-combmatlons or portlons or sald system could be independently utilized, so that the invention is not to be restricted to the complete combination described herein.

I have shown preferred embodiments of my "invention, but it is clear that numerous changes and omissions could be made without departing from its spirit.

I claim:

1. A scale device for an exposure meter comprising a first inovable member, said member having thereon a first scale indicating stop values and a second scale indicating' plate emulsion speeds, said scales being space from each other, a second member, said second mem-ber having an index adjacent to and cooperatin with said second scale, and a third mem er movable with respectto both the other members and having an index adapted to cooperate with said first scale.

2. A scaledevice for an exposure meterv comprising a rst movable member, said member having thereon a first scale indicatingvstop values and a second scale indicatlng plate emulsion speeds, said scales being spaced from each other, a second member, said second member having an index adjacent to and cooperating with said second scale,` and a third member movable with respect to both the other members andV having an index adapted to-cooperate with said first scale. said v of lines connecting the indications o said first tors thereon adjacent said second scale, said third relatively movable member being adapted to he set in accordance with light. conditions present, said second member havin a series'- sc`a-le substantially to theV outer edge of Vsaid third member, so that said lines dlrectly cooperate with the index of the third member, the outer ends 'of said lines being unequally 'said third member in ing light conditions.

3. A scale device for an exposure meter comprising a first movable member, said accordance with varymember having thereon a first scale indicating stop values and a second scale indicating plate emulsion speeds, said scales being spaced from each other, a second member, said second member having an index adjacent to and cooperatin with said second scale, and a third mem er movable with respect to both the other members and having an index adapted to coo erate with said first scale, said sec: ond mem -er also having a scale of filter facscales being correspondingly graduated to cooperatewith cach other.

4L A scale device for .an exposure meter comprising a first movable member, said member having thereon a first scale indicating stop values and a second scale indicating plate emulsion speeds, said scales being spaced from each other, a -secon d member, said second member having an index adjacent to and cooperating with said second scale, and a third l member movable with respect to both 'the other members and having an index adapted to cooperate with said rst scale, and a fourth member having a scale indicating exposure times, said scale of exposure times bein adj acent to and being correspondingly gra uated to the scale of exposure stop values.

' 5. A scale device for an exposure meter comprising a first movable member, said member having thereon a first scale indicating stop values and a second scale indicatingplate emulsion speeds, said scales being spaced from each other, a second member, sa1d second Y member having an index adjacent to and cooperating with said second scale, and a third member movable with respect to both the other members and having an index adapted to cooperate with said first scale, said third movable member being adapted to be set in accordance with light conditions present, said second'member `having a series of lines connectin the indications of said first scale substantia y to the outer edge of said .third member, so that said lines directly cooperate with the index of the third member, the outer ends of said lines being unequally spaced to corre-v spond with the movement of said third member in accordance with varying ,light conditions, and `a fourth member having a scale indicating exposure timessaid scale of exksaid second member having an index adja- :mansov posure ytimes being .adjacent to and beinV correspondingly graduated to the scale o stop values.' l

6. A scale, device for an vexposure meter comlising a first movable member, said member aving thereon a rstscale indicating stop values and a second scale'- indicating plate emulsion speeds, said, scales bein spaced from each other, a'second member, sa1d second ,spaced to correspond with the movement of member having anl index adjacent to and cooperating with said second scale, anda third member movable with respect to both the other members and having an index adapted to cooperate with said first scale, and a fourth member having an additional scale of the number of exposures per second, said additional scale bein adjacentv to and being correspond/ingly gra uated to the scale of stop values,

7. A scale device for an exposure meter comprising a first movable member, said member having thereon'a first scale indicating stop values and a second scale indicating plate emulsionl speeds, said scales being spaced from each other, a second member,

cent to and cooperating with said second scale, and a third member movable with respect to both the other members and havin an index adapted to cooperate with said first scale, and a fourth member having an additional scale of the number of exposures per second, said additional scale being ad'acent to and being correspondingly vgr uated tothe scale of stop values, a portion of the scale of sto values. being specially indicated for color. inemato a hy. In testimony whereof gli; m si ature.

` JOSEPH ING. 

